Commands or functionsA small portion of a program that’s set aside and given a name. It helps isolate key code in an easy-to-understand way, and it makes changes easier and less error prone. It’s a really important way to make programs easier to understand. May also be called a subroutine. that let a programmer control some other program or objectWhen talking about programs, these are “things” that can be created in a way that encapsulates the details, letting them be accessed from outside through an interface. or thing, or get data from some object, without knowing the details of how it works.
Inside the Internet of Things - Bryon Moyer Blog